Hub enabled single hop transport forward access

ABSTRACT

A satellite system is configured to receive and allow direct forwarding of traffic on a time slot by time slot basis without demodulation or decoding. The satellite system may be configured to receive waveforms and configured to separate a waveform of data from a waveform of control information. The satellite system may be configured to switch the waveform of data toward one or more terminals and configured to switch the waveform of control information toward a satellite control unit without demodulation or decoding of the waveforms. A method for satellite communication is also provided.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of priority from U.S. ProvisionalPatent Application Ser. No. 61/808,613, entitled, “HUB ENABLED JAMMEREXCISION,” filed on Apr. 4, 2013, which is hereby incorporated byreference in its entirety for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD

The disclosure relates in general to satellite communication, and moreparticularly to, for example, without limitation, a hub enabled singlehop transport forward access (HFA) mode.

BACKGROUND

A satellite commination system may include an uplink(s) and adownlink(s). The uplink may be a portion of a communication link usedfor transmission of signals from a ground terminal to a satellite. Thedownlink may be a portion of a communication link used for transmissionof signals from a satellite to a ground terminal Purely transpondedsatellite systems send all signals received on the uplink to ahub/gateway for processing and may require a multitude of hub/gateways,therefore greatly increasing overall system cost and vulnerability, andreducing system reliability and overall traffic capacity.

The description provided in the background section, including withoutlimitation, any problems, features, solutions or information, should notbe assumed to be prior art merely because it is mentioned in orassociated with the background section. The background section mayinclude information that describes one or more aspects of the subjecttechnology.

SUMMARY

The description in this summary section may provide some illustrativeexamples of the disclosure. This section is not intended to be a broadoverview or to identify essential elements of the disclosure.

In one or more implementations, a satellite system is configured toreceive and allow direct forwarding of traffic on a time slot by timeslot basis without demodulation or decoding. The satellite system may beconfigured to receive waveforms and configured to separate a waveform ofdata from a waveform of control information. The satellite system may beconfigured to switch the waveform of data toward one or more terminalsand configured to switch the waveform of control information toward asatellite control unit without demodulation or decoding of thewaveforms.

In one or more implementations, a method for satellite communication mayinclude receiving waveforms associated with one or more uplinks betweena satellite and at least one terminal and separating waveforms of datafrom waveforms of control information. The method may include forwardingthe waveforms of data on a time slot by time slot basis for one or moredownlinks between the satellite and one or more terminals and forwardingthe waveforms of control information on a time slot by time slot basisto a satellite control unit. The method may include dynamically alteringuplink signal robustness and rate based on uplink measurements providedby the satellite control unit, dynamically altering downlink signalrobustness and rate based on downlink measurements provided by thesatellite control unit, and dynamically varying a playback rate of thewaveforms of data for downlink based on the downlink measurements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an example of a satellite servicing a large geographicarea, where the satellite utilizes hub enabled single hop transportforward access (HFA).

FIG. 2 illustrates an example of a single HFA low latency single hopin-theater data path.

FIG. 3A depicts an example of an HFA-enabled satellite system.

FIG. 3B depicts an example of a Waveform Store and Forward (WSAF) moduleand an example of its operation.

FIG. 4 depicts an example of an uplink signal format.

FIG. 5 depicts an example of a downlink signal format.

FIG. 6 depicts an example of mapping of HFA uplink frames to downlinkframes.

FIG. 7 illustrates an example of separation of control and data trafficwhen an HFA mode is supported for direct connection between two or moreterminals.

FIG. 8 illustrates an exemplary configuration for cross-connection andresource allocation using HFA.

FIG. 9 illustrates an example of connectivity group(s) and resourceallocation.

FIG. 10 is a block diagram illustrating an example of a computer systemwith which some implementations of the subject technology can beimplemented.

DETAILED DESCRIPTION

It is understood that various configurations of the subject technologywill become readily apparent to those skilled in the art from thedisclosure, wherein various configurations of the subject technology areshown and described by way of illustration. As will be realized, thesubject technology is capable of other and different configurations andits several details are capable of modification in various otherrespects, all without departing from the scope of the subjecttechnology. Accordingly, the summary, drawings and detailed descriptionare to be regarded as illustrative in nature and not as restrictive.

The detailed description set forth below is intended as a description ofvarious configurations of the subject technology and is not intended torepresent the only configurations in which the subject technology may bepracticed. The appended drawings are incorporated herein and constitutea part of the detailed description. The detailed description includesspecific details for the purpose of providing a thorough understandingof the subject technology. However, it will be apparent to those skilledin the art that the subject technology may be practiced without thesespecific details. In some instances, well-known structures andcomponents are shown in block diagram form in order to avoid obscuringthe concepts of the subject technology. Like components are labeled withidentical element numbers for ease of understanding. Some of the wordsor phrases are expressed using one or more capital letters forconvenience only and do not limit its meaning in any manner.

Hub Enabled Single Hop Transport Forward Access

In one or more implementations, a hub enabled single hop transportforward access (HFA) mode is a communication satellite operating modemotivated by the need for an affordable giga-bit-per-second (Gbps) classsatellite that increases capacity and service flexibility, reduceslatency, increases system security, reduces ground infrastructure andcost, simplifies control and planning, and increases robustness toelectronic warfare (EW) threats such as jamming.

Purely transponded satellite systems send all signals received on theuplink to a hub/gateway for processing, including signals with bothsource and destination terminals in direct view of the satellite. Thepurely transponded satellite system may incur four major signalpropagation delays: (1) terminal-to-satellite delay, (2)satellite-to-hub/gateway delay, (3) hub/gateway-to-satellite delay, and(4) satellite-to-destination terminal delay. For communication betweenterminals within view of the satellite, purely transponded systems mayincur two unnecessary relay delays. The two unnecessary relay delays mayinclude one unnecessary relay delay from the satellite to a hub/gatewayover a feeder link for the uplink traffic (e.g., as discussed in (2)above) and an additional unnecessary relay delay from the hub/gateway tothe satellite over the feeder link for the downlink traffic (e.g., asdiscussed in (3) above). Furthermore, purely transponded satellitesystems may require far more complex and higher capacity feeder links tosupport the unnecessary relays to the gateway/hub than would benecessary if all communication between terminals within direct view ofthe satellite were direct (e.g., avoiding the hub/gateway relays). Apurely transponded system may require a multitude of hub/gateways,therefore greatly increasing overall system cost and vulnerability, andreducing system reliability and overall traffic capacity. Thehub/gateway feeder link may often become a major traffic bottleneck.

There may be several potential problems with direct routing of signalsbetween terminals that lie within direct view of the satellite. First,uplink and downlink data rates, bandwidths, and time slots may often beincommensurate. For example, a 20-MHz uplink is not directly compatiblewith a 150-MHz downlink. Modulation and coding may not be directlycompatible. For example, uplink Quadrature Phase-Shift Keying (QPSK)modulation with Low-Density Parity Check (LDPC) coding would not becompatible with downlink 8-PSK with turbo coding. Furthermore, downlinksmay be often shared by all terminals (e.g., broadcast), whereas uplinksare Time Division Multiple Access (TDMA). In addition, direct relay ofthe uplink signal onto the downlink may involve complex demodulation andre-modulation of the signal on the satellite, which increases satellitecomplexity and cost. In addition, in one or more implementations, uplinksignals must have a control component that must be routed to a satellitesystem controller (SSC) and not the destination terminal Thus, directrelay of the uplink signal to the destination terminal might not relaythe terminal control signal to the SSC. There could be potentialproblems with uplink and downlink synchronization. A method to allowbroadcast or multicast from the uplink to any or all of the downlinkbeams, as well as unicast of uplink signals to the downlink would alsoneed to be provided.

In one or more implementations, the present disclosure addresses amethod to allow direct relay (e.g., no gateway/hub relay) of signalsthat have both source and destination terminals within view of any ofthe beams of the satellite. The present disclosure offers, among others,significant latency reduction, Quality of Service (QoS) improvement,system cost and vulnerability advantages. A significant portion of thesatellite traffic may be carried in this mode since satellite coverageareas are immense and it is most often the case that the source anddestination terminal are in view of the satellite. In one or moreaspects, the present disclosure allows unicast, multicast, or broadcastof downlink signals onto any or all downlink beams. In one or moreaspects, the present disclosure allows for both time and carriersynchronization of the relayed signal by the destination receiver. Inone or more aspects, the present disclosure reduces satellite cost andcomplexity by not requiring demodulation or decoding of the signalreceived by the satellite prior to relay.

FIG. 1 depicts an example of a satellite servicing a large geographicarea, where the satellite utilizes hub enabled single hop transportforward access (HFA). Data communication 110 (e.g., in-theater traffic)may often constitute 90% or more of all user traffic in typical usage.HFA may allow a multitude of users to communicate with single hop (e.g.,terminal 104A to satellite 118, and satellite 118 to terminal 104B), lowlatency, high quality service directly through the satellite to thedestination terminal, completely bypassing any hub/gateway (e.g.,hub/gateway 106A-106B). HFA may thereby limit the proliferation ofhubs/gateways that would otherwise be required to support this capacitylevel. Minimizing hub/gateway infrastructure may be a key driver inreducing overall satellite system cost and vulnerability, improvingQuality of Service (QoS), and increasing security. HFA may be fullycompatible with “double hop” user-to-gateway traffic (e.g., controlcommunication 112) for the small fraction of reach back traffic that maybe required to be sent to a system control unit 108. System control unit108 may include one or more hubs and/or gateways. Alternatively, or inaddition, system control unit 108 may comprise or represent a satellitesystem controller (SSC). HFA mode can be integrated on a Dehop RehopTransponded (DRT) payload supporting: wideband frequency hopping (e.g.,multiple GHz) for EW protection, advanced adaptable multi-modemodulation and coding, and advanced spatial/temporal interferencecancellation that reduces vulnerability to EW threats (e.g., from jammer102). Uplink 114 includes one or more uplink signals from terminal 104Ato satellite 118. Downlink 116 includes one or more downlink signalsfrom satellite 118 to terminal 104B. As noted above, uplink and downlinkdata rates, bandwidths, and time slots may often be incommensurate. Inone or more implementations, uplink 114, downlink 116 and controlcommunication 112 involve wireless communications, and each of satellite118, terminals 104A and 104B, and system control unit 108 are remotefrom each other.

HFA Data Path

FIG. 2 illustrates an example of a single HFA low latency single hopin-theater data path. Source terminal 202 may transmit one or moresignals including, for example, data and control information. The datamay be destined for a destination terminal 204 (e.g., anotherin-coverage-area terminal). The control information may be sent tosystem control unit 206. The transmitted one or more signals may befrequency hopped. The transmitted one or more signals may propagate upto a satellite 222, for example, as one or more uplink signals via anuplink 224. Satellite 222 may receive the transmitted one or moresignals, down convert or dehop them using a down converter or dehopper210, thereby eliminating most of the EW jammer energy. Satellite 222 maydigitize, extract and separate all uplink signals at a channelizer 212(e.g., digital channelizer). An advanced spatial/temporal interferencecancellation may further mitigate jammer energy via a spatial temporalanti jammer 214.

Uplink signals including, for example, uplink beams, channels, and timeslots designated for an HFA mode may be waveform stored and forwarded tothe appropriate downlink beam by Waveform Store and Forward (WSAF)module 216. WSAF module 216 may separate data from control information,switch data to forward link unit 218, and switch control information tofeeder link unit 220. In one or more implementations, forward link unit218 may include one or more digital-to-analog converters, one or moreupconverters and one or more high power amplifiers. In one or moreimplementations, feeder link unit 220 may include one or moredigital-to-analog converters, one or more upconverters and one or morehigh power amplifiers.

Data may be replayed at the appropriate time and bandwidth (e.g., viaplayback rate adjustment) on a downlink beam via forward link unit 218,while control information may be separately routed via feeder link unit220. The replayed data (e.g., in-theater user data) may be transmittedon downlink 226 directly to destination terminal 204. Controlinformation may be sent to system control unit 206 via feeder link 228.System control unit 206 may be in communication with gateway 208 and/orinclude one or more gateways. Further, system control unit 206 mayrepresent one or more hubs and/or include or represent satellite systemcontroller (SSC). Control information may be processed at system controlunit 206 or at a space vehicle in some configurations. Alternatively orin addition, processing of the control information may be optimallysplit between a satellite and a system control unit.

FIG. 3A depicts an example of an HFA-enabled satellite system. Itillustrates an example of a detailed view of the fullmulti-beam/multi-channel signal processing associated with an HFA mode.A satellite system 301 may include down converters 302,analog-to-digital converters (ADCs) 304, channelizers 306, WaveformStore and Forward (WSAF) module 308, digital-to-analog converters (DACs)and upconverters 310, and high power amplifiers (HPA) 312. Downconverters 302 may be in communication with antennas. HPA 312 may be incommunication with antennas.

In one or more aspects, down converters 302 may correspond to downconverter or dehopper 210 of FIG. 2. In one or more aspects,channelizers 306 may correspond to channelizer 212 of FIG. 2. In one ormore aspects, Waveform Store and Forward (WSAF) module 308 maycorrespond to Waveform Store and Forward (WSAF) module 216 of FIG. 2.DACs and upconverters 310 and HPA 312 may correspond to forward linkunit 218 of FIG. 2. While ADCs are not shown in FIG. 2, in one or moreimplementations, the system of FIG. 2 includes ADCs (e.g., ADCs 304)between down converter or dehopper 210 and channelizer 212.

Multiple beams may be received by down converters 302 via antennas fromone or more source terminals. While FIG. 3A shows uplink beam 1 throughuplink beam A, the subject technology is not limited thereto. A portionof the spectrum in each beam may be down converted to a low intermediatefrequency (IF) by the respective one of down converters 302 and sampledby the respective one of ADCs 304. Each digital IF signal from each beammay contain one or more Time Division Multiple Access (TDMA) channelsthat are active within each beam.

A total of M uplink channels and A uplink beams are depicted in FIG. 3A;however, the subject technology is not limited thereto, and can apply toother multiples of uplink channels and beams, as well as to groupings ofdifferent uplink channels and beams. Each channel associated with itsrespective beam is digitally isolated and converted to digital basebandin channelizers 306 (e.g., uplink channelizers). Each channelizedbaseband signal may be passed to Waveform Store and Forward (WSAF)module 308. Waveform Store and Forward (WSAF) module 308 may includeuplink interface 316 and downlink interface 318. Each downlink signalfrom the downlink interface 318 may be converted to analog form via theDACs and upconverters 310 (e.g., upconverted in frequency to RF), andamplified by HPA 312.

FIG. 3B depicts an example of a Waveform Store and Forward (WSAF) moduleand an example of its operation. As noted above, Waveform Store andForward (WSAF) module 308 may include uplink interface 316 and downlinkinterface 318. A WSAF uplink (UL) memory controller 322 may cause theuplink waveform associated with each TDMA slot operating in HFA mode tobe stored in the appropriate one of the uplink memories (e.g., UL memory320). Downlink (DL) memory controller 326 may forward the capturedwaveform to the appropriate downlink (DL) memory (e.g., DL memory 324)associated with the assigned destination beam(s) and channel via ahigh-speed interconnect fabric. The high-speed interconnect fabricallows signal forwarding from M uplink channels/beams, to any of Ndownlink channels/beams as illustrated in FIG. 3B. A total of M uplinkchannels/beams and N downlink channels/beams are depicted in FIG. 3B;however, the subject technology is not limited thereto, and can apply toother multiples of uplink and downlink channels/beams, as well as togroupings of different uplink and downlink channels/beams.

The WSAF module 308 may extract waveform(s) from downlink memories(e.g., DL memory 324) and replay them on the appropriate downlink beamand channel in the time slot assigned by the satellite system controller(SSC), and at a rate commensurate with the downlink bandwidth (BW)(e.g., maximum downlink BW, or less, as commanded by SSC). Controlsignals associated with HFA transmissions may be separated by WSAFmodule 308 and sent over via data and control interface 328 to the SSC.The SSC may load the forwarding tables (e.g., a switching look-up table)from the ground via the feeder link (e.g., feeder link 228 of FIG. 2)and feeder link unit (e.g., feeder link unit 220). Using the forwardingtables, WSAF 308 may control forwarding of the signal associated withuplink beam, channel, and time slots to downlink beams, channels, timeslots. Alternatively, or in addition, using the forwarding tables, WSAFmodule 308 may control extraction of control signals and theirforwarding to the SSC.

One or More Aspects of Features

Single Hop Transport

For many communication satellites, the majority of user data traffic isbetween terminals within view of the satellite. This traffic cantheoretically be relayed from one or more source terminals to one ormore destination terminals directly through a single satellite, eitheras inter-beam traffic or intra-beam traffic, without the need for anintermediary hop over a feeder link to a ground-based hub/gateway forprocessing. In such systems, single hop user data traffic may betransmitted from the source terminal via the uplink to a satellite,which is sometimes referred to as a space vehicle (SV). The SV mayreceive and process the uplink signal, switch and transmit the signaldirectly on the appropriate downlink beam and channel to the one or moredestination terminals. Single hop transfer may reduce overall datatraffic latency since no intermediary transmission to and from ahub/gateway via a feeder link is required. Single hop user data transfermay also increase the Quality of Service (QoS) since overallterminal-to-terminal signal latency is reduced vis-à-vis a hub-basedsatellite relay system. In one or more implementations, HFA can providesingle hop transfer of data.

Reduced Hubs/Gateways

In purely transponded satellite systems, a hub/gateway is a ground basedprocessing center. All uplink user traffic received by a satellite maybe relayed via a feeder link to the hub/gateway for processing andswitching. In-theater traffic may be then relayed back up the feederlink for subsequent transmission on the appropriate satellite downlink(DL) beam and channel to the ultimate destination terminal. A typicalhub/gateway based satellite system may require a multitude ofhubs/gateways. Low cost satellite systems may seek to reduce oraltogether eliminate the number of hubs and gateways to reduce overallsystem cost, reduce user data signal delay, improve Quality of Service(QoS), and reduce security and vulnerability concerns associated withhubs and gateways.

One or More Aspects of Details of HFA

Uplink Format

FIG. 4 depicts an example of an uplink frame format. HFA allows eachsatellite to support multiple uplink beams (e.g., uplink beams 1 throughP), with each satellite beam including one or many channels (e.g.,channels 1 through M, channels 1 through N, and channels 1 through O) asdepicted in FIG. 4. HFA allows a multitude of bandwidths to be supportedby each channel (e.g., uplink channel). Each channel may have a TimeDivision Multiple Access (TDMA) format. Specific users may be assignedspecific beams, channels, and time slots (e.g., 402A-402C) by thesatellite system controller (SSC). The channels may or may not befrequency hopped (e.g., shown as not hopping in FIG. 4). There may be norestriction on the modulation used by the uplink. The satellite mayprovide some (e.g., unspecified) method to keep terminals aligned intheir TDMA slots (e.g., usually implemented by a method of rangingsignal). The uplink signal may support carrier synchronization in theform of embedded phase reference symbols in each TDMA burst.

Downlink Format

FIG. 5 depicts an example of a downlink frame format. HFA may utilizeone or more downlink channels as depicted in FIG. 5. HFA may allow amultitude of downlink bandwidths. In one or more implementations, HFAmay not use a TDMA format over the full downlink frame; however, in oneor more implementations, the HFA mode does require that a portion of thedownlink time is dedicated to HFA signals, and during the time allocatedto downlink HFA mode a TDMA format is used. The bandwidth utilized byHFA downlink may be equal to or less than the maximum downlink bandwidthassigned to the channel. In one or more implementations, the modulationand coding used on the HFA downlink time slot conforms to the modulationand coding used by the uplink signal mapped to each downlink time slot.

Mapping between Uplink and Downlink

FIG. 6 depicts an example of mapping of HFA uplink frames to thedownlink frames. Time slots designed for transport in HFA mode may bedigitally sampled by the satellite, stored, and the stored signal may bereplayed (e.g., forwarded) at the appropriate time and rate (e.g., tomatch the desired downlink bandwidth) on the designated downlink HFAtime slot as discussed in details with reference to FIG. 3B. In one ormore implementations, no demodulation or decoding of the uplink signalis made at the satellite (e.g., by a Waveform Store and Forward (WSAF)module or other components of the satellite) prior to forwarding thesignal onto the downlink; only the uplink waveform is forwarded verbatimon the downlink. In one or more implementations, control time slots areseparately sampled, utilizing a WSAF module, but are not sent to thedestination terminal; instead, control time slots are forwarded,utilizing a WSAF module, to the satellite system controller (SSC) fordemodulation, decoding, and processing.

Waveform Store and Forward (WSAF)

According to one or more implementations, exemplary operations of aWaveform Store and Forward (WSAF) module is illustrated. A WSAF modulemay be sometimes referred to as WSAF circuits. A WSAF module allows thewaveform associated with each uplink TDMA time slot in each channeloperated in HFA mode to be digitally sampled and briefly stored on oneor more memories of the satellite. In one or more implementations, nodemodulation or decoding is performed on the waveform by the WSAF moduleor any other components of the satellite. The WSAF module causes thewaveform itself (e.g., without demodulation) to be briefly stored at thesatellite for replay. In one or more implementations, the WSAF modulecan replay the appropriate uplink waveform (or uplink signal) on thedownlink channel and time slot associated with the destination terminalin HFA mode, or terminals (e.g., the channels and time slots for HFAmode that are previously assigned by the satellite system controller(SSC)). The WSAF module can cause the stored uplink waveform to bereplayed on the appropriated forward link (downlink) beam, channel, andtime slot at a rate associated with the maximum bandwidth of thedownlink channel; or, if necessary, at a lower rate necessary to allowlink closure and communication, taking into account the downlink channelconditions. The downlink channel conditions may include noise, jamming,mobility, receiver antenna obstructions, destination terminal size(e.g., large, medium, or small). Lowering the playback rate of thestored waveform on the downlink may increase the Energy per Bit to noisedensity ratio (Eb/No) received by the destination terminal (e.g., at thecost of lower throughput rate) and therefore may increase linkrobustness. This method of varying the playback rate of the waveform tomatch downlink channel conditions (e.g., weather, jamming, antennaobstructions, terminal size) and maximum downlink bandwidth mayeffectively decouple the uplink signal robustness from the downlinksignal robustness. This may allow the SSC to dynamically andindependently adjust the uplink (e.g., coding, modulation, and/orbandwidth) and downlink bandwidth to meet the conditions of each link(e.g., weather, jamming, noise, terminal size) independently.

Control Channel (e.g., Terminal to SSC, Uplink)

In HFA mode, separate uplink time slots (e.g., time orthogonal) orchannels (e.g., frequency orthogonal) for terminal to satellite systemcontroller (SSC) communications may be assigned (e.g., a controlchannel). Control time slots and/or a separate control channel may beassigned to each uplink terminal operating in HFA mode by the SSC. Thetime slots or frequency used by the control channel may be orthogonal tothe HFA data. In one or more implementations, a WSAF module can causeuplink control signals to be sampled and separately forwarded tosatellite system controller (SSC) for processing and not forwarded tothe destination terminal at all. Having separate uplink control and datatime slots may increase system robustness and security since the dataand control planes have been separated. Separation of data and controlplane may allow satellite to centrally control connectivity among agroup of user terminals. This may allow satellite user terminals to havetheir own secure virtual private network over an HFA enabled satellite.This may simplify the satellite design since only control channels needto be demodulated by the satellite system controller (SSC). In one ormore implementations, a WSAF module causes system control messages to beseparated and forwarded to the SSC and not the destination terminal;this is because all control for HFA mode is commanded by the SSC, so allcontrol messages from terminals are forwarded by the WSAF module to theSSC.

Control Channel (e.g., SSC to Terminal, Downlink)

In one or more implementations, the control channel from the SSC to theterminal is unspecified in the present disclosure, but a control pathexists on the non-HFA portion of the downlink between the SSC and eachterminal.

HFA Features

Elimination of Gateways via HFA

In one or more implementations, HFA eliminates nearly all ground hubsand gateways and their associated complexity, delay, and securityvulnerability. In one or more implementations of HFA, a WSAF modulecauses the waveforms of all inter-theater uplink signals to be brieflystored and then directly forwarded on the appropriate downlink beams,channels, and time slots, thus reducing or altogether eliminatinghub/gateway traffic. In one or more implementations, only trafficspecifically destined for a gateway needs to be relayed through the hubto a gateway (e.g., reach back traffic).

Modulation Independence

In one or more implementations, HFA is compatible with any or all typesof modulation that is transmitted during an uplink channel time slot. Inone or more implementations, HFA simply samples the uplink waveform,briefly stores it, and forwards it on the appropriate downlink beam,channel, and time slot, utilizing a WSAF module. In one or moreimplementations, an HFA-enabled satellite does not demodulate thewaveform; so no specific baud, phase nor frequency synchronizers,demodulators nor remodulators, hard nor soft decision slicers, or pulseshaping filters are required by the HFA-enabled satellite. Further anHFA-enabled satellite can operate with any modulation. This allows theterminals to largely implement modifications to the burst size,modulation, and coding independent of the satellite so far as the basicterminal-to-satellite uplink TDMA and satellite-to-terminal downlinkcharacteristics are maintained; thus future-proofing the originalsatellite investment.

Uplink Per Time Slot Circuit Switch (PTSCS)

In one or more implementations, HFA receives uplink signals on time slotboundaries (e.g., for each uplink beam and channel), waveform stores,and forwards (WSAF) on the appropriate downlink beam, channel, and timeslot. The process of sampling and storing the waveform for each uplinktime slot, and forwarding the waveform on the appropriate downlink beam,channel, and time slot may be a form of circuit switching (e.g., PerTime Slot Circuit Switching, PTSCS). This process may be performed bythe Waveform Store and Forward (WSAF) module. The space vehicle (SV) maymaintain a switching look-up table that maps uplink beam, channel time,and time slots to forward link beam, channel, and time slots. Theswitching table can be updated in real-time to dynamically alter theterminal-to-terminal connectivity. The WSAF module may utilize theswitching look-up table in connection with storing and forwarding thewaveform.

Uplink Per Uplink Time Slot Circuit Multi-Cast (PTSMC)

In one or more implementations, after receiving uplink signals each timeslot (e.g., for each uplink channel and uplink beam), Waveform Store andForward (WSAF) can also forward the stored waveform on multiple downlinkbeams simultaneously, effectively creating multi-cast or broadcastmessages (e.g., Per Time Slot Multi-Cast, PTSMC). The space vehicle (SV)may maintain a switching look-up table that maps uplink beams, channelsand time slots to multiple downlink beams and time slots to enablemulti-cast and broadcast services. The WSAF module may utilize theswitching look-up table in connection with storing and forwarding thewaveform.

Independent Downlink and Uplink Modes

In one or more implementations, an HFA-enabled satellite (via e.g., aWSAF module) allows the satellite system controller (SSC) to select thedownlink bandwidth for each downlink beam and channel independently ofthe uplink modulation or coding. This allows the SSC to efficientlyrespond to the downlink channel conditions. The downlink channelconditions may include jamming, noise, weather, user antenna blockage,terminal size (e.g., large, medium, or small) independently of theuplink modulation and coding. In one or more implementations, this isextremely important since many downlink and uplink link budget elementsare independent (e.g., weather, jamming, noise, terminal size), so theSSC may need to be able to independently set the robustness level of thedownlink. Lowering the downlink bandwidth by reducing the waveformplayback rate may increase the downlink robustness to, for example,weather, jamming, terminal size, but lower the throughput rate. In oneor more implementations, SSC may provide the control information (e.g.,channel conditions and switching look-up tables) to a satellite via afeeder link unit to be used by a Waveform Store and Forward (WSAF)module. The feeder link unit may include one or more channels,downconvertors, upconvertors, ADCs and/or DACs. In one or moreimplementations, the feeder link unit includes one or more downconverters and ADCs for the control information transmitted by SSC tothe satellite. The feeder link may use a different frequency band thanthe uplink and/or downlink. Alternatively or in addition, uplink anddownlink may use the same or different frequency band.

Control and Data Channel Separation

In one or more implementations, an HFA-enabled satellite (via e.g., aWSAF module) uses separate uplink time slots and/or a separate purecontrol channel for data and control for each channel and each uplinkbeam. For each uplink beam and channel a control circuit may be set upusing uplink time slots and/or a separate pure control channel selectedby the SSC. This separation of data and control via uplink channel timeslots allows the satellite (e.g., a WSAF module) to extract controlinformation at the payload and process it independently of the dataplane signals that are forwarded onto the downlink.

FIG. 7 illustrates an example of separation of control and data trafficwhen an HFA mode is supported for direct connection between two or moreterminals. Return link 704A/704B may be a point-to-point link betweensatellite 710 and terminal 714A/714B, respectively. Forward link702A/702B may be broadcast links to some or all terminals with acoverage area. The aggregated traffic between satellite 710 and systemcontrol unit 716 may be carried over a wideband link with a differentchannelization and structure. Non-HFA data traffic 706 may include datatraffic destined to one or more hubs/gateways. Control traffic 708 maybe destined to system control unit 716 (e.g., SSC). Point-to-pointreturn link (e.g., return link 704A or 704B) may include data time slots(e.g., represented by crosshatch in FIG. 7) and control time slots(e.g., represented by solid black in FIG. 7). Broadcast forward link(e.g., 702A or 702B) may include data time slots for terminal 714A or714B (e.g., represented by crosshatch in FIG. 7), control time slots(e.g., represented by solid black in FIG. 7), and data time slotsdestined to other terminals in the coverage area (e.g., different fromterminal 714A or 714B), which are, for example, represented by solidwhite in FIG. 7.

Forwarding Table

A mission management (MM) function can set up terminal-to-terminal(s)HFA paths a priori through mission planning. This may simplify terminalsetup but is not as dynamic for user IP networks.Terminal-to-terminal(s) paths may also be setup dynamically on demand.Terminal Connectivity Groups within a satellite network can support pathsetup mechanisms typically supported by layer 2/3 overlay networks. Thisadds terminal complexity but provides dynamic setup based on terminaldemand. Multiple options and multiple techniques are possible, includingbut not limited to the following: (1) Resource Reservation Protocol(RSVP)-like path setup, (2) Session Initiation Protocol (SIP) signalingfor voice calls, and (3) Generic Routing Encapsulation (GRE) tunnelsetup. Mixed Mode could also be supported. For example, one ConnectivityGroup can be planned through mission management while another is setupdynamically.

Terminal Logon

When a terminal logs on to a satellite system controller, it registerswith the satellite system controller by providing a list of useraddresses (e.g., MAC addresses or VLAN tags or IP address prefixes)reachable on its user interface (protocol dependent, e.g., SIP). Theterminal decides what information about its networks should be exposedto the satellite network. The satellite network similarly does notexpose any information about its internal network to the terminal user.It is completely opaque to the user networks. The terminal builds itsapplicable reachability tables independently as an overlay over thesatellite network. The terminal only has an understanding about itsConnectivity Group(s) and any required information. The satellitenetwork does not know and does not need to know anything about the usernetwork topology.

Forwarding Table Construction and Forwarding

In one or more implementations, a satellite system controller buildsconnectivity HFA forwarding tables among all logged-in users within eachconnectivity group based upon information and labels provided by eachterminal during system login, and login standardized protocols (e.g.,SIP, RSVP, GRE, etc.). The connectivity forwarding tables link theappropriate HFA uplink beam, channel, and time slot(s) to downlinkbeam(s), channel(s), and time slot(s) by setting up a cross-connect.Relevant forwarding table information is transmitted to each terminal ineach connectivity group via the downlink non-HFA mode controlcommunication. This login process allows each terminal to know HFAdownlink and uplink time slots used for each of its connectivity groups.

Within a connectivity group many terminal connection types shown inTable 1 but not limited to the list provided in the table can besupported. Table 1, thus, provides some examples, but the subjecttechnology is not limited to these examples.

TABLE 1 Connection Types Connection Type Description Point-to-Point Aone-way connection between two terminals where Half Duplex one terminalis in transmit mode and the (or Simplex) second terminal is in receiveonly mode. On the satellite the transmitting terminal return linkbeam(s), channel(s), time slot(s) are mapped to receiving terminalbeam(s), channel(s), time slot(s). Point-to-Point A two-way connectionbetween two terminals where Full Duplex 1) Terminal 1 transmits data toTerminal 2, and receives data from Terminal 2, and 2) Terminal 2transmits data to Terminal 1, and receives data from Terminal 1. On thesatellite the transmitting terminal return link beam(s), channel(s),time slot(s) are mapped to receiving terminal beam(s), channel(s), timeslot(s). The connection between the two terminals can be symmetric(e.g., same data rate supported in both directions) or asymmetric (e.g.,different data rates are supported in each direction). Many Receivers Aone-way connection from a transmitting terminal One Transmitter is timeshared by two or more terminals. Each Half Duplex connection is ahalf-duplex one-way connection Time Shared between the transmitting andreceiving terminal and Transmit is independent of connections to otherreceiving Connection terminals in the time-shared terminal group becausethe connection is orthogonal in time to other receiving terminals in thetime-shared terminal group. In a time-shared system only one connectionis active at an instance of time between the transmitter and one of thereceiving terminals of the time-shared group. As an example, Terminal 1transmits to Terminal 2 during allocated time T2 for reception onTerminal 2 and transmits to Terminal 3 during allocated time T3 forreception on Terminal 3. The receiving terminals may be located indifferent antennas/beams and different channels. The mapping defined onthe satellite ensures data destined for two terminals (e.g., return linkbeam(s), channel(s) and time slot(s)) are appropriately mapped onforward link destined for terminal 1 and terminal 2 beam(s), channel(S)and time slot(s) respectively. Many This connection is exactly oppositesetup to Half Transmitters Duplex Time Shared Transmit Connection. A OneReceiver one-way time shared connection from many Half Duplextransmitting terminals to single receive terminal Time Shared is set up.Each connection is a half-duplex one- Receive way connection betweentransmitting terminal Connection and the receiving terminal and isindependent of connections to other transmitting terminals in thetime-shared terminal group because the connection is orthogonal in timeto other transmitting terminals in the time-shared terminal group. In atime-shared system only one connection is active at an instance of timebetween the receiver and one of the transmitting terminals of thetime-shared group. As an example, Terminal 1 receives transmitted datafrom Terminal 2 during allocated time T2 and Terminal 1 receivestransmitted data from Terminal 3 during allocated time T3. Thetransmitting terminals may be located in different antennas/ beams anddifferent channels. The mapping defined on the satellite ensures datadestined from two terminals T2 and T3 (e.g., return link beam(s),channel(s) and time slot(s)) are appropriately mapped on forward linkdestined for Terminal 1 beam(s), channel(s) and time slot(s). BroadcastData is broadcast by a terminal to one or more Connection terminals overtheir respective forward links. Terminal 1 transmits on allocatedbeam(s), Channel(s), and Time slot(s) to Terminals 2 through N.Terminals 2 through N receive on their allocated beam(s), Channel(s),and Time slot(s). Satellite maps the return link data from transmittingterminal and makes copies for receiving terminals. The receivingterminals may be located in different antennas/beams and differentchannels.

FIG. 8 illustrates an exemplary configuration for cross-connection andresource allocation using HFA.

Connectivity group supports both HFA and non-HFA mode connections. HFAcross-connects between return link beam(s), channel(s), and time slot(s)and forward link beam(s), channel(s) and time slot(s) are setup on thesatellite based on the desired connection. These circuit-likeconnections may be either pre-planned or dynamically setup according tothe supported protocols on the terminals and at the hub/gateway.

FIG. 8 and Table 2 illustrate one example of time slot mapping performedfor the connectivity group including five terminals. However, thesubject technology is not limited thereto, and can apply to othermultiples of terminals, as well as to groupings of different terminals.

As depicted in Table 2, column Tx is the transmitting terminal Column RLis the return link entry for the connectivity. Column Rx is thereceiving terminal Column FL is the forward link entry for theconnectivity.

TABLE 2 Exemplary Forwarding Table: Cross-Connect Map Tx RL Rx FL 1 T1T13 T3 R13 2 T3 T31 T1 R31 3 T3 T3S T2 R32 4 T4 R34 5 T5 R35 6 T3 T3HHub Hub Link

In some aspects, Terminal 1 and Terminal 3 have a bidirectionalpoint-to-point full duplex connection (e.g., represented by entries inrows 1-2 of Table 2). This is an HFA mode entry. Terminal 3 istransmitting to terminals 2, 4, and 5 using a half-duplex time-sharedconnection (e.g., represented by entries in rows 3-5 of Table 2). Thisis an HFA mode entry. Terminal 3 is also connected to a hub in ahalf-duplex manner (e.g., represented by entries in row 6 of Table 2).This is a non-HFA mode entry.

FIG. 8 and Table 3 illustrate another example of time slot mappingperformed for the connectivity group including five terminals. However,the subject technology is not limited thereto, and can apply to othermultiples of terminals, as well as to groupings of different terminals.

TABLE 3 Exemplary Forwarding Table: Cross-Connect Map Tx RL Rx FL 1 T2T23 T3 R23 2 T3 T32 T2 R32 3 T3 T31 T1 R1S 4 T4 T41 5 T4 T4N T2 R42 6 T5R45 7 T5 T51 T1 R51

In some aspects, Terminal 2 and Terminal 3 have a bidirectionalpoint-to-point full duplex connection (e.g., represented by entries inrows 1-2 of Table 3). This is an HFA mode entry. Terminal 3 and Terminal4 are transmitting terminal(s) connected to receiving Terminal 1 using apoint-to-point half duplex time-shared connection (e.g., represented byentries in rows 3-4 of Table 3). This is an HFA mode entry. Terminal 4has a multicast connection to Terminal 2 and 5 (e.g., represented byentries in rows 5-6 of Table 3). Terminal 5 is connected to Terminal 1over a half-duplex connection (e.g., represented by entries in row 7 ofTable 3).

FIG. 9 illustrates an example of connectivity group(s) and resourceallocation. In one or more implementations, a satellite systemcontroller allocates resources by apportioning satellite resources formultiple connectivity groups. Adjustment to HFA connectivity betweendifferent terminals and cross-connects on the satellite are made by theresource allocation software hosted on the satellite system controller.

In one or more implementations, optional resource allocation within aconnectivity group can be hosted on one of the terminals in theconnectivity group. Resource allocation within a connectivity group isperformed by the designated terminal hosting resource allocation incoordination with the satellite system controller resource allocationmaster.

Uplink Transmitting Terminal Operation

When a user packet arrives at the uplink terminal with a destinationaddress identifier (protocol dependent, e.g., SIP) associated with aparticular Connectivity Group, the terminal forwards that packet if ithas an HFA path (beam(s), channel(s), time slot(s)) already setup forthat Connectivity Group. Otherwise, the terminal forwards the packet toa satellite system controller as a default-forwarding path using non-HFAmode.

In one or more implementations, a satellite system controller decides ifthe packet should be forwarded to a known destination terminal. It mayforward the packet to the intended known destination, or may decide todrop the packet silently (e.g., assuming connectivity is not permitted).The satellite system controller may proceed to set up an HFAcross-connect on the space vehicle. In one or more implementations, allsubsequent packets from the source terminal will be directly forwardedto the destination terminal using HFA mode.

Satellite Operation

The satellite forwards, using a Waveform Store and Forward module, HFAuplink time slots (in the associated uplink beam and channel) to theappropriate downlink beam(s), channels(s) and time slot(s) based on theHFA forwarding tables.

Downlink Receiving Terminal Operation

Each receiving terminal demodulates and decodes the signal in each HFAtime slot associated with its Connectivity Groups and forwards thedecoded bits to the intended destination Connectivity Group.

Example of Functions and Components

In one or more implementations, an HFA-enabled satellite does notperform demodulation on waveforms before forwarding them to anappropriate downlink(s). Examples of demodulation not performed at thesatellite may include digital demodulation such as some or all of thefollowing: (i) bandpass demodulation based on, for example, phase shiftkeying, frequency shift keying, or amplitude shift keying (e.g., varioustypes of PSK (e.g., QPSK, BPSK), FSK, ASK, QAM), and/or (ii) basebanddemodulation for reducing intersymbol interference or for providingequalization. In one aspect, an HFA-enabled satellite does not performany of the demodulation listed above.

In one or more implementations, an HFA-enabled satellite does notperform decoding on waveforms before forwarding them to an appropriatedownlink(s). Examples of decoding not carried out at the satellite mayinclude digital decoding such as some or all of the following: channeldecoding (e.g., Forward Error Correction (FEC) decoding), decrypting,and/or source decoding. In one aspect, an HFA-enabled satellite does notperform any of the decoding listed above.

In one or more implementations, an HFA-enabled satellite does nottransform waveforms into bits or streams of bits. Referring to FIG. 3A,after analog waveforms are converted into digital waveforms (e.g., byADCs 304), the digital waveforms (e.g., waveforms of data and waveformsof control information) are not transformed into bits or streams of bitswhile being processed on the satellite. The digital waveforms may be,for example, digital bandpass waveforms or digital baseband waveforms.In FIG. 3A, data and control waveforms are not transformed into bits orstreams of bits along the path between down converters 302 and HPAs 312.Waveforms may be transformed into bits or streams of bits at thedestination terminal(s) or a system control unit(s), but not at thesatellite.

Descriptions related to demodulation, decoding and waveforms are alsoprovided in a book by Bernard Sklar, entitled, “DigitalCommunications—Fundamentals and Applications,” Second Edition, PrenticeHall PTR, 2001, which is hereby incorporated by reference in itsentirety for all purposes.

In one or more implementations, control information that may be providedfrom a satellite to a system control unit and vice versa may include oneor more of the following: mapping between the uplink beams, channels,and time slots and the downlink beams, channels, and time slots (e.g.,switching look-up tables) and uplink and/or downlink channel conditions(e.g., weather, jamming, antenna blockage, noise and/or terminal size).

Example of Computer System

FIG. 10 is a block diagram illustrating an example of computer system1000 with which some configuration of the subject technology can beimplemented. In certain aspects, computer system 1000 may be implementedusing hardware or a combination of software and hardware, either in adedicated computer or server, or integrated into another entity, ordistributed across multiple entities. Each of a satellite, terminal,system control unit, satellite system controller, hub, and gateway maycomprise a computer system 1000 to perform various operations describedherein.

Computer system 1000 includes a bus 1008 or other communicationmechanism for communicating information, and a processor 1002 coupledwith bus 1008 for processing information. By way of example, thecomputer system 1000 may be implemented with one or more processors1002. Processor 1002 may be a general-purpose microprocessor, amicrocontroller, a Digital Signal Processor (DSP), an ApplicationSpecific Integrated Circuit (ASIC), a Field Programmable Gate Array(FPGA), a Programmable Logic Device (PLD), a controller, a statemachine, gated logic, discrete hardware components, or any othersuitable entity that can perform calculations or other manipulations ofinformation.

Computer system 1000 can include, in addition to hardware, code thatcreates an execution environment for the computer program in question,e.g., code that constitutes processor firmware, a protocol stack, adatabase management system, an operating system, or a combination of oneor more of them stored in an included memory 1004, such as a RandomAccess Memory (RAM), a flash memory, a Read Only Memory (ROM), aProgrammable Read-Only Memory (PROM), an Erasable PROM (EPROM),registers, a hard disk, a removable disk, a CD-ROM, a DVD, or any othersuitable storage device, coupled to bus 1008 for storing information andinstructions to be executed by processor 1002. For example, the memory1004 includes instructions for implementing hub enabled signal hoptransport forward access (HFA) mode. The processor 1002 and the memory1004 can be supplemented by, or incorporated in, special purpose logiccircuitry.

The instructions may be stored in the memory 1004 and implemented in oneor more computer program products, i.e., one or more modules of computerprogram instructions encoded on a computer readable medium for executionby, or to control the operation of, the computer system 1000.Instructions may be implemented in various computer languages. Memory1004 may be used for storing temporary variable or other intermediateinformation during execution of instructions to be executed by processor1002.

A computer program can be deployed to be executed on one computer or onmultiple computers that are located at one site or distributed acrossmultiple sites and interconnected by a communication network. Theprocesses and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output.

Computer system 1000 further includes a data storage device 1006 such asa magnetic disk, optical disk or solid-state disk, Static Random AccessMemory (SRAM) and Dynamic Random Access Memory (DRAM), coupled to bus1008 for storing information and instructions. Computer system 1000 maybe coupled via input/output module 1010 to various devices. Theinput/output module 1010 can be any input/output module. Theinput/output module 1010 is configured to connect to a communicationsmodule 1012. Example communications modules 1012 include networkinginterface cards. In certain aspects, the input/output module 1010 isconfigured to connect to a plurality of devices, such as an input device1014 and/or an output device 1016. Example input devices 1014 includeone or more ADCs. Example output devices 1016 include one or more DACs.

The term “machine-readable storage medium” or “computer readable medium”as used herein refers to any medium or media that participates inproviding instructions or data to processor 1002 for execution. Such amedium may take many forms, including, but not limited to, non-volatilemedia, and volatile media.

Illustration of Subject Technology as Clauses

Various examples of aspects of the disclosure are described as numberedclauses below (e.g., 1, 2, 3, etc.) for convenience. These are providedas examples, and do not limit the subject technology.

-   -   1. A satellite system that allows direct forwarding of        in-theater traffic on a time-slot by time slot basis, without        the need for demodulation or decoding.    -   2. A satellite system that allows per channel, per beam, per        time slot, waveform sample forwarding between uplink and        appropriate downlink beams, channels and time slots.    -   3. A satellite system that allows modulation independent signal        transponding between uplink beams, channels and time slots onto        appropriate downlink beams, channels and time slots.    -   4. A satellite system that allows independent bandwidth rate        adjustments between uplink and downlink transponded signal via        Waveform Store and Forward (WSAF) to accommodate independent        channel conditions between the downlink and uplink (e.g. noise,        jamming, antenna blockage, terminal size).    -   5. A satellite system that Waveform Stores and Forward (WSAF)        uplink time slots for each channel and beam onto appropriate        downlink channels, beams and time slots.    -   6. A satellite system that allows fast unicast switching between        uplink beams, channels and time slots and downlink beams,        channels, and time slots.    -   7. A satellite system that allows fast multicast switching        between uplink beams, channels and time slots and downlink        beams, channels, and time slots.    -   8. A satellite system that allows fast broadcast switching        between uplink beams, channels and time slots and downlink        beams, channels, and time slots.    -   9. A satellite system that allows separation of control and data        between uplink beams, channels and time slots.    -   10. A satellite system that allows forwarding of uplink beam,        channel, and time slot to downlink beam, channel, and time slot        based on look-up tables assigned dynamically by a satellite        system controller.    -   11. A satellite system method of dynamically altering downlink        and uplink signal robustness and data rate based on uplink and        downlink measurements, varying downlink modulation and coding        and varying WSAF playback rate on the downlink.    -   12. A satellite system that allows satellite operator to        centrally control connectivity among a group of user terminals        allowing a group of terminals to implement a virtual private        network over an HFA enabled satellite.    -   13. A satellite system method of setting up a point-to-point        half-duplex (or simplex) one-way connection from a transmitting        terminal to a receiving terminal using WSAF over an HFA enabled        satellite.    -   14. A satellite system method of setting up a point-to-point        full duplex two-way connection between two terminals where 1)        Terminal 1 transmits data to Terminal 2, and receives data from        Terminal 2, and 2) Terminal 2 transmits data to Terminal 1, and        receives data from Terminal 1 using WSAF over an HFA enabled        satellite.    -   15. A satellite system method of setting up a point-to-point        full duplex two-way asymmetric connection between two terminals        where rates are different in each direction using WSAF over an        HFA enabled satellite.    -   16. A satellite system method of setting up a point-to-point        full duplex two-way symmetric connection between two terminals        where rates are identical in either direction using WSAF over an        HFA enabled satellite.    -   17. A satellite system method of setting up a half-duplex time        shared connection consisting of many receiving terminals and one        transmitting terminal using WSAF over an HFA enabled satellite.    -   18. A satellite system method of setting up a half-duplex time        shared connection consisting of many transmitting terminals and        one receiving terminal using WSAF over an HFA enabled satellite.    -   19. A satellite system method of setting up broadcast connection        consisting of many receiving terminals and one transmitting        terminal using WSAF over an HFA enabled satellite.    -   20. A satellite system method of setting up connections using a        combination of techniques listed in clauses 15 through 19 but        not limited to techniques listed in clauses 15 through 19 using        WSAF over an HFA enabled satellite.

Other Descriptions

In one aspect, any of the clauses herein may depend from any one of theindependent clauses or any one of the dependent clauses. In one aspect,any of the clauses (e.g., dependent or independent clauses) may becombined with any other one or more clauses (e.g., dependent orindependent clauses). In one aspect, a claim may include some or all ofthe words (e.g., steps, operations, means or components) recited in aclause, a sentence, a phrase or a paragraph. In one aspect, a claim mayinclude some or all of the words recited in one or more clauses,sentences, phrases or paragraphs. In one aspect, some of the words ineach of the clauses, sentences, phrases or paragraphs may be removed. Inone aspect, additional words or elements may be added to a clause, asentence, a phrase or a paragraph. In one aspect, the subject technologymay be implemented without utilizing some of the components, elements,functions or operations described herein. In one aspect, the subjecttechnology may be implemented utilizing additional components, elements,functions or operations.

In one aspect, any methods, instructions, code, means, logic,components, blocks, modules and the like (e.g., software or hardware)described or claimed herein can be represented in drawings (e.g., flowcharts, block diagrams), such drawings (regardless of whether explicitlyshown or not) are expressly incorporated herein by reference, and suchdrawings (if not yet explicitly shown) can be added to the disclosurewithout constituting new matter. For brevity, some (but not necessarilyall) of the clauses/descriptions/claims are explicitly represented indrawings, but any of the clauses/descriptions/claims can be representedin drawings in a manner similar to those drawings explicitly shown. Forexample, a flow chart can be drawn for any of the clauses, sentences orclaims for a method such that each operation or step is connected to thenext operation or step by an arrow. In another example, a block diagramcan be drawn for any of the clauses, sentences or claims havingmeans-for elements (e.g., means for performing an action) such that eachmeans-for element can be represented as a module for element (e.g., amodule for performing an action).

Those of skill in the art would appreciate that items such as thevarious illustrative blocks, modules, elements, components, methods,operations, steps, and algorithms described herein (e.g., Waveform Storeand Forward (WSAF) module therein) may be implemented as hardware,computer software, or a combination of both.

To illustrate the interchangeability of hardware and software, itemssuch as the various illustrative blocks, modules, elements, components,methods, operations, steps, and algorithms have been described generallyin terms of their functionality. Whether such functionality isimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.Skilled artisans may implement the described functionality in varyingways for each particular application.

In one aspect, means, a block, a module, an element, a component or aprocessor may be an item (e.g., one or more of blocks, modules,elements, components or processors) for performing one or more functionsor operations. In one aspect, such an item may be an apparatus,hardware, or a portion thereof. In an example, an item may beimplemented as one or more circuits configured to perform thefunction(s) or operation(s). A circuit may include one or more circuitsand/or logic. A circuit may be analog and/or digital. A circuit may beelectrical and/or optical. A circuit may include transistors. In anexample, one or more items may be implemented as a processing system(e.g., a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA),etc.), a portion(s) or a combination(s) of any of the foregoing. In oneexample, an item may have a structure in the form of, for example, aninstruction(s) encoded or stored on a machine-readable medium, onanother device, or on a portion thereof. An instruction(s) may besoftware, an application(s), a subroutine(s), or a portion thereof forperforming the function(s) or operation(s). The instruction(s) may beexecutable by one or more processors. Those skilled in the art willrecognize how to implement the circuits, processing systems,instructions and a combination thereof.

In one aspect of the disclosure, when actions or functions (e.g.,receiving, converting, transmitting, or any other action or function)are described as being performed by an item (e.g., one or more ofblocks, modules, elements, components or processors), it is understoodthat such actions or functions may be performed, for example, by theitem directly. In another example, when an item is described asperforming an action, the item may be understood to perform the actionindirectly, for example, by facilitating such an action (e.g.,assisting, allowing, enabling, causing, or providing for, such action tooccur; or performing a portion of such an action). For example,receiving can refer to facilitating receiving, and transmitting canrefer to facilitating transmitting. In one aspect, performing an actionmay refer to performing a portion of the action (e.g., performing abeginning part of the action, performing an end part of the action, orperforming a middle portion of the action).

Unless specifically stated otherwise, the term some refers to one ormore. Pronouns in the masculine (e.g., his) include the feminine andneuter gender (e.g., her and its) and vice versa. Headings andsubheadings, if any, are used for convenience only and do not limit theinvention.

The word exemplary is used herein to mean serving as an example orillustration. Any aspect or design described herein as exemplary is notnecessarily to be construed as preferred or advantageous over otheraspects or designs. In one aspect, various alternative configurationsand operations described herein may be considered to be at leastequivalent.

Phrases such as an aspect, the aspect, another aspect, some aspects, oneor more aspects, an implementation, the implementation, anotherimplementation, some implementations, one or more implementations, anembodiment, the embodiment, another embodiment, some embodiments, one ormore embodiments, a configuration, the configuration, anotherconfiguration, some configurations, one or more configurations, thesubject technology, the disclosure, the present disclosure, othervariations thereof and alike are for convenience and do not imply that adisclosure relating to such phrase(s) is essential to the subjecttechnology or that such disclosure applies to all configurations of thesubject technology. A disclosure relating to such phrase(s) may apply toall configurations, or one or more configurations. A disclosure relatingto such phrase(s) may provide one or more examples. A phrase such as anaspect or some aspects may refer to one or more aspects and vice versa,and this applies similarly to other foregoing phrases.

In one aspect, unless otherwise stated, all measurements, values,ratings, positions, magnitudes, sizes, and other specifications that areset forth in this specification, including in the claims that follow,are approximate, not exact. In one aspect, they are intended to have areasonable range that is consistent with the functions to which theyrelate and with what is customary in the art to which they pertain. Inone aspect, some of the dimensions are for clarity of presentation andare not to scale.

Various items may be arranged differently (e.g., arranged in a differentorder, or partitioned in a different way) all without departing from thescope of the subject technology. In one aspect of the disclosure, theelements recited in the accompanying claims may be performed by one ormore modules or sub-modules.

It is understood that the specific order or hierarchy of steps,operations or processes disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of steps, operations or processes may berearranged. Some of the steps, operations or processes may be performedsimultaneously. Some or all of the steps, operations, or processes maybe performed automatically, without the intervention of a user. Theaccompanying method claims, if any, present elements of the varioussteps, operations or processes in a sample order, and are not meant tobe limited to the specific order or hierarchy presented.

The disclosure is provided to enable any person skilled in the art topractice the various aspects described herein. The disclosure providesvarious examples of the subject technology, and the subject technologyis not limited to these examples. Various modifications to these aspectswill be readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other aspects.

All structural and functional equivalents to the elements of the variousaspects described throughout this disclosure that are known or latercome to be known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe claims. Moreover, nothing disclosed herein is intended to bededicated to the public regardless of whether such disclosure isexplicitly recited in the claims. No claim element is to be construedunder the provisions of 35 U.S.C. §112, sixth paragraph, unless theelement is expressly recited using a phrase means for or, in the case ofa method claim, the element is recited using the phrase step for.Furthermore, to the extent that the term include, have, or the like isused, such term is intended to be inclusive in a manner similar to theterm comprise as comprise is interpreted when employed as a transitionalword in a claim.

The Title, Background, Summary, Brief Description of the Drawings andAbstract of the disclosure are hereby incorporated into the disclosureand are provided as illustrative examples of the disclosure, not asrestrictive descriptions. It is submitted with the understanding thatthey will not be used to limit the scope or meaning of the claims. Inaddition, in the Detailed Description, it can be seen that thedescription provides illustrative examples and the various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed subject matter requires morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of a single disclosed configuration or operation. The followingclaims are hereby incorporated into the Detailed Description, with eachclaim standing on its own as a separately claimed subject matter.

The claims are not intended to be limited to the aspects describedherein, but is to be accorded the full scope consistent with thelanguage claims and to encompass all legal equivalents. Notwithstanding,none of the claims are intended to embrace subject matter that fails tosatisfy the requirement of 35 U.S.C. §101, 102, or 103, nor should theybe interpreted in such a way. Any unintended embracement of such subjectmatter is hereby disclaimed.

What is claimed is:
 1. A method for satellite communication, comprising:receiving, at a satellite, waveforms associated with one or more uplinksbetween the satellite and at least one terminal; storing, temporarily inone or more uplink memories of a waveform store and forward (WSAF)module of the satellite, the received waveforms; separating, with theWSAF module of the satellite, waveforms of data and waveforms of controlinformation from within the stored waveforms based on uplink channeltime slots; forwarding, to one or more downlink memories within the WSAFmodule of the satellite, the waveforms of data on a time slot by timeslot basis for one or more downlinks between the satellite and one ormore terminals; forwarding the waveforms of control information on atime slot by time slot basis to a satellite control unit; dynamicallyaltering uplink signal robustness and rate based on uplink measurementsprovided by the satellite control unit; dynamically altering downlinksignal robustness and rate based on downlink measurements provided bythe satellite control unit; and dynamically varying a playback rate ofthe waveforms of data for downlink based on the downlink measurements.2. The method of claim 1, wherein a group of user terminals comprisesthe at least one terminal and the one or more terminals, and the methodallows centrally controlling connectivity among the group of userterminals allowing a group of terminals to implement a virtual privatenetwork.
 3. The method of claim 1, comprising one or more of thefollowing operations performed utilizing the waveform store and forward(WSAF) module of the satellite: setting up a point-to-point half-duplexor simplex one-way communication connection from a transmitting terminalto a receiving terminal; setting up a point-to-point full duplex two-waycommunication connection between two terminals to allow (i) a first oneof the two terminals to transmit data to the second one of the twoterminals, (ii) the first one of the two terminals to receive data fromthe second one of the two terminals, (iii) the second one of the twoterminals to transmit data to the first one of the two terminals, and(iv) the second one of the two terminals to receive data from the firstone of the two terminals; setting up a point-to-point full duplextwo-way asymmetric communication connection between at least twoterminals, wherein communication rates are different in each directionof the point-to-point full duplex two-way asymmetric communicationconnection, wherein the at least one terminal comprises the transmittingterminal, wherein the one or more terminals comprise the receivingterminal, wherein the at least one terminal and the one or moreterminals comprise the two terminals, and wherein the at least oneterminal and the one or more terminals comprise the at least twoterminals.
 4. The method of claim 1, comprising: setting up apoint-to-point full duplex two-way symmetric communication connectionbetween two terminals, utilizing the waveform store and forward (WSAF)module of the satellite, wherein communication rates are identical ineither direction of the point-to-point full duplex two-way symmetriccommunication connection, wherein the at least one terminal and the oneor more terminals comprise the two terminals.
 5. The method of claim 1,comprising: setting up a half-duplex time shared communicationconnection for a group of terminals consisting of a plurality ofreceiving terminals and one transmitting terminal, utilizing thewaveform store and forward (WSAF) module of the satellite, wherein theat least one terminal comprises the one transmitting terminal, andwherein the one or more terminals comprise the plurality of receivingterminals.
 6. The method of claim 1, comprising: setting up ahalf-duplex time shared communication connection for a group ofterminals consisting of a plurality of transmitting terminals and onereceiving terminal, utilizing the waveform store and forward (WSAF)module of the satellite, wherein the at least one terminal comprises theplurality of transmitting terminals, and wherein the one or moreterminals comprise the one receiving terminal.
 7. The method of claim 1,comprising: setting up a broadcast connection for a group of terminalsconsisting of a plurality of receiving terminals and one transmittingterminal, utilizing the waveform store and forward (WSAF) module of thesatellite.